REFLECTOR: Ground Testing Update

Fri Feb 15 13:35:31 CST 2013

I feel your pain... you are doing the right things by not rushing through the process just to get into the air.  Work the problem and keep charging.  I'm new to the site and am learning from the 'lists' collective experience.  What engine do you have?

Regards,
Luis
Velocity XL-5 "Dulcinea"

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Subject: Reflector Digest, Vol 95, Issue 12

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Today's Topics:

   1.  Ground Testing Update (Brian Michalk)

----------------------------------------------------------------------

Message: 1
Date: Thu, 14 Feb 2013 22:09:45 -0600
From: Brian Michalk <michalk at awpi.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Subject: REFLECTOR: Ground Testing Update
Message-ID: <511DB509.4010201 at awpi.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

It's been quiet here, so here's something to fill the void.

I've been on the cusp of my second first flight for almost four months 
now.  Man, it's been a long time.  My primary problem is that I just 
haven't been able to make rated horsepower, and it's been due to three 
reasons.

1.  The impulse coupler spring on my magneto broke.
I ordered a spare alternator, and it was about 40 days from ordering to 
delivery.  I continued to do ground testing with the bad coupler, 
knowing that the timing was anywhere between 0TDC and 32 TDC.

2. The mixture was too rich.
I spent about four hours tuning the engine in November, starting over 
from scratch on the electronic tables that map RPM and manifold pressure 
to a fuel flow.  If you recall, my first flight four years ago was due 
to an over-rich condition.  Well, I tuned to 50F ROP. After I got the 
magneto in, I still couldn't make power.  I brought the plane back and 
ran static at full throttle, leaning out the mixture.  Sure enough, the 
RPM's came up, so I tuned to max RPM, then richened until the RPMS 
dropped slightly.  This should be a safe mixture for the first flight.  
It turns out that I have my engine monitor set for Celsius instead of 
Fahrenheit.

3.  The turbo is seized.
This is the final discovery made this weekend.  It's either spark, fuel 
or air, and this was the final problem I hope.  About 20 engine hours 
ago I put a restriction in the oil line to the turbo to keep from 
blowing oil through the seals.  Apparently my calculations for the 
restriction are wrong.  I pulled the turbo and sent it out for repair, 
estimated to be about $350.

It's been very frustrating.  I have been set up for my "first flight" on 
about four different occasions, only to shut her down in the takeoff 
roll because of not accelerating through 80 knots.  I've had the plane 
very light on the wheels.  Nose up, one or the other mains up, but no 
acceleration through rotation.  I bet I've gone through 15 to 20 high 
speed taxis like this, and I'm ready to just fly the airplane.  This 
turbo problem better be the solution.  I'm out of ideas if it's not.  On 
the first flight four years ago, there was plenty of power.  Same fuel 
system, induction and ignition, so I know the engine is capable of 
making the power.

------------------------------

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End of Reflector Digest, Vol 95, Issue 12
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